Stationary exercise bicycle

ABSTRACT

A stationary exercise bicycle includes a base, and right and left pedals mounted to the base. The pedals are configured to rotate in operation about an axis of rotation. A frame has a rear end pivotally mounted to the base, and a forward end spaced apart from the rear end. A saddle is coupled to the rear end of the frame, and a handlebar is coupled to the forward end of the frame. The stationary exercise bicycle includes an actuator coupling the frame to the base. The actuator is configured to pivot the frame relative to the base about the axis of rotation, which can enable the rider to maintain the same general position as the frame is pivoted between normal and inclined positions.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No. 61/534,919 filed on Sep. 15, 2011, the entire contents of which are hereby incorporated herein by reference.

FIELD

The present disclosure relates to a stationary exercise bicycle for indoor cycling.

BACKGROUND

The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.

Indoor cycling, often referred to as SPINNING™, is a form of exercise that involves using a stationary exercise bicycle in a classroom setting. A typical class can involve a single instructor at the front of the class who leads participants through routines that are designed to simulate terrain and situations similar to riding a road bicycle outdoors. Some of the movements and positions include hill climbs, sprints and interval training. The instructor can use music, motivation, visualization and enthusiastic coaching to lead students through a ride that suits their fitness level and goals. An advantage of indoor cycling is that each participant can control his/her level of intensity to suit their individual ability or fitness level, but still remain as a part of a group.

Indoor cycling classes generally use specialized stationary bicycles. Features of these bicycles can include a mechanical device to modify the difficulty of pedaling, specially shaped handlebars offering various positions, and multiple adjustment points to fit the bicycle to a range of riders. The bicycles can also include a weighted flywheel which simulates the effects of inertia and momentum when riding a real bicycle. Typically, the difficulty of the workout can be modulated by the individual in two ways: by varying the resistance to the flywheel attached to the pedals; and/or by changing the cadence (the speed at which the rider pedals).

INTRODUCTION

The following paragraphs are intended to introduce the reader to the more detailed description that follows and not to define or limit the claimed subject matter.

According to an aspect of the present disclosure, a stationary exercise bicycle can include: a base; right and left pedals coupled to the base, and configured to rotate in operation about an axis of rotation; a frame having a rear end pivotally mounted to the base, and a forward end spaced apart from the rear end; a saddle coupled generally to the rear end of the frame; a handlebar coupled generally to the forward end of the frame; and an actuator coupling the frame to the base, the actuator configured to pivot the frame relative to the base about the axis of rotation.

According to an aspect of the present disclosure, a stationary exercise bicycle can include: a base; a frame; a crank assembly pivotally coupling the frame to the base, the crank assembly comprising a spindle; right and left pedals mounted to the spindle, and configured to rotate in operation about an axis of rotation; and a hydraulic cylinder coupling the frame to the base, the hydraulic cylinder configured to pivot the frame relative to the base about the axis of rotation between normal and inclined positions.

According to an aspect of the present disclosure, a stationary exercise bicycle can include: a base; right and left pedals coupled to the base, and configured to rotate in operation about an axis of rotation; a frame coupled to the base, the frame comprising a saddle and a handlebar; and a linear actuator coupling the frame to the base, the linear actuator configured to pivot the frame relative to the base about the axis of rotation between normal and inclined positions.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings included herewith are for illustrating various examples of apparatuses and methods of the present disclosure and are not intended to limit the scope of what is taught in any way. In the drawings:

FIG. 1 is perspective view of a stationary exercise bicycle;

FIG. 2 is a top view of the stationary exercise bicycle of FIG. 1;

FIG. 3 is a side view of the stationary exercise bicycle of FIG. 1, in which a frame of the stationary exercise bicycle is shown in a normal position;

FIG. 4 is a side view of the stationary exercise bicycle of FIG. 1, in which the frame is shown in an inclined position;

FIG. 5 is an exploded view of several parts of the stationary exercise bicycle of FIG. 1;

FIGS. 6A and 6B are detailed perspective views of a crank assembly of the stationary exercise bicycle of FIG. 1, with and without crank arms and pedals, respectively;

FIG. 7 is an exploded perspective view of the crank assembly of FIGS. 6A and 6B;

FIG. 8 is schematic flow diagram of a hydraulic system;

FIG. 9 is a detailed perspective view of another crank assembly of the stationary exercise bicycle of FIG. 1; and

FIG. 10 is an exploded perspective view of the crank assembly of FIG. 9.

DETAILED DESCRIPTION

Various apparatuses or methods are described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover apparatuses and methods that differ from those described below. The claimed inventions are not limited to apparatuses and methods having all of the features of any one apparatus or method described below or to features common to multiple or all of the apparatuses or methods described below. It is possible that an apparatus or method described below is not an embodiment of any claimed invention. Any invention disclosed in an apparatus or method described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicant(s), inventor(s) and/or owner(s) do not intend to abandon, disclaim or dedicate to the public any such invention by its disclosure in this document.

Referring to FIGS. 1, 2 and 3, an example of a stationary exercise bicycle is shown generally at 10.

The stationary exercise bicycle 10 includes a base 12. In the example illustrated, the base 12 is formed of a longitudinal base member 14 which extends between a rearward lateral base member 16 and a forward lateral base member 18. Outer ends of the lateral base members 16, 18 include ground engaging feet 20.

The stationary exercise bicycle 10 includes right and left pedals 22 a, 22 b coupled to the base 12. The pedals 22 a, 22 b rotate in operation about an axis of rotation 24.

The stationary exercise bicycle 10 includes a frame 26. The frame 26 has a rearward end 26 a pivotally mounted to the base 12, and a forward end 26 b spaced apart from the rearward end 26 a.

In the example illustrated, the frame 26 includes a seat tube 28 at the rearward end 26 a, and a head tube 30 at the forward end 26 b. The seat and head tubes 28, 30 are arranged generally upright, and the angle of each can be varied, as can the dimension between them, depending on desired geometry. For example, and not intended to be limiting, the seat tube 28 can be arranged, when in a normal position, at an angle of approximately 7 degrees aft, whereas the head tube 30 can be arranged at an angle of approximately 15 degrees aft. Furthermore, a horizontal distance between centers of the seat and head tubes 28, 30 (measured at the top of the seat tube 28) can be approximately 592 mm.

In the example illustrated, the frame 26 further includes a first top tube 32 extending generally between the seat and head tubes 28, 30. A first down tube 34 is connected between the head and top tubes 30, 32. As illustrated, the frame 26 can also include a second top tube 36 and a second down tube 38 which extend generally between the seat and head tubes 28, 30. The top tubes 32, 36 are spaced apart to accommodate a crank assembly (described below). In some examples, the frame 26 can be formed from 2″ structural steel tubing having a ⅛″ wall thickness, and with a powder coat. With the tubes 28, 30, 32, 34, 36, 38 secured (e.g., welded) to one another, the frame 26 can be a relatively rigid structure.

A seat post 40 is received in the seat tube 28, and couples a saddle 42 to the rearward end 26 a of the frame 26. An adjustment mechanism 44 can be provided to lock the position of the seat post 40 relative to the seat tube 28, to set the height of the saddle 42 as desired. As illustrated, a generally horizontal seat slide bar 46 is mounted to the seat post 40. A sleeve 48 slides over the slide bar 46. The saddle 42 is fixed to the sleeve 48. An adjustment mechanism (not shown) can be provided to lock the position of the sleeve 48 relative to the slide bar 46, to set the fore/aft position of the saddle 42.

Similarly, a head post 50 is received in the head tube 30, and couples a handlebar 52 to the forward end 26 b of the frame 26. An adjustment mechanism 54 can be provided to lock the position of the head post 50 relative to the head tube 30, to set the height of the handlebar 52 as desired. As illustrated, a generally horizontal head slide bar 56 is mounted to the head post 50. A sleeve 58 slides over the slide bar 56. The handlebar 52 is fixed to the sleeve 58 via a bracket 60. As with handlebars on a typical road bicycle, the bracket 60 can allow for the position of the handlebar 52 to be raised or lowered (by pivoting about the bracket 60) as desired. An adjustment mechanism (not shown) can be provided to lock the position of the sleeve 58 relative to the slide bar 56, to set the fore/aft position of the handlebar 52.

Mounting plates 62, 64 are secured to the base member 14. In the example illustrated, right and left cradle plates 66 a, 66 b are secured to the mounting plate 62 using, for example, fasteners (not shown). As illustrated, the cradle plates 66 a, 66 b can be arranged to be upstanding, generally parallel to one another. The rearward end 26 a of the frame 26 is arranged between, and pivotally supported by, the cradle plates 66 a, 66 b, as described in further detail below.

An actuator 68 couples the frame 26 to the base 12. In the example illustrated, the actuator 68 is a linear actuator, with a lower end secured to the mounting plate 64 at a pivotal connection 70. An upper end of the actuator 68 is secured to the forward end 26 b of the frame 26 at a pivotal connection 72, via a pair of mounting plates 74. The mounting plates 74 are arranged on either side of a junction between the head tube 30 and the second down tube 38 of the frame 26.

Referring to FIGS. 3 and 4, the actuator 68 can pivot the frame 26 relative to the base 12 about the axis of rotation 24 between a normal position (in which the actuator 68 is retracted, shown in FIG. 3) and an inclined position (in which the actuator 68 is extended, shown in FIG. 4). The frame 26 pivots about the axis of rotation 24 between the normal and inclined positions. In the normal position the top tube 32 is aligned with line 76 a, whereas in the inclined position the top tube 32 is aligned with line 76 b. The lines 76 a, 76 b define an incline angle 78. The incline angle 78 is zero when in the normal position. In some examples, the incline angle 78 can be up to about 15 degrees in the inclined position. In some examples, the incline angle 78 can be up to about 20 degrees in the inclined position.

As mentioned above, indoor cycling classes can use specialized stationary bicycles. If a rider's position is not optimal on the stationary bicycle, injuries can occur. Problems with the lower back and knees are the most common types of injuries that can be sustained using stationary bicycles. To avoid injury, the biomechanical position of the rider should be established, and maintained, as closely to optimal as possible.

With this in mind, the frame 26 of the stationary exercise bicycle 10 rotates about the axis of rotation 24 of pedals 22 a, 22 b, which can enable the rider to maintain the same general position as the frame 26 is pivoted between the normal and inclined positions. In other words, the relative distances between the pedals 22 a, 22 b, the saddle 42 and the handlebar 52 (the points of contact between the rider and the stationary exercise bicycle 10) are the same when the frame 26 is in the normal and inclined positions, and any intermediate position in between the normal and inclined positions. As such, the biomechanical position of the rider is maintained, and the risk of injury can be reduced.

As illustrated in FIGS. 1, 2 and 3, the stationary exercise bicycle 10 can include a control device 80. The control device 80 includes a means for user input (for example, a mechanical lever, buttons, and/or a touch screen), and can include a means for providing information to the user (for example, a liquid crystal display). In the example illustrated, the control device 80 is mounted to the sleeve 58, but various configurations are possible. In other examples, the control device can consist of two or more components arranged in separate locations on the stationary exercise bicycle 10.

In some examples, the control device 80 can be used to command the actuator 68 to move the frame 26 between the normal and inclined positions. Furthermore, optionally, the control device 80 can be used to control a resistance of the pedals 22 a, 22 b. In some examples, the resistance can be increased as the incline angle 78 increases between the normal and inclined positions. In some examples, the resistance can be proportional to the incline angle 78, thereby simulating a hill climb. Moreover, in some examples, the control device 80 can be used to control the resistance of the pedals 22 a, 22 b independent of the incline angle 78 (e.g., to increase resistance to simulate wind).

In some examples, the stationary exercise bicycle 10 can utilize hydraulics. As illustrated, the actuator 68 can comprise a hydraulic cylinder. For the purposes of clarity, hydraulic connections between the actuator 68 and other components of the stationary exercise bicycle 10 have been omitted from the drawings.

Referring now to FIGS. 5, 6A and 6B, a crank assembly 82 is coupled to the pedals 22 a, 22 b by crank arms 84 a, 84 b, respectively. The crank assembly 82 can be configured to drive hydraulic fluid from an inlet port 88 to an outlet port 86, as described in further detail below.

The crank assembly 82 can be secured to the frame 26, with fasteners (not shown), between tubes 28, 32, 36, and arranged between the cradle plates 66 a, 66 b (which are secured to the base 12, as shown in FIG. 1). The cradle plates 66 a, 66 b can be secured to one another and maintained in a spaced apart relationship using spacers 90 and spacing block 92, along with fasteners (not shown). Bearings 94 a, 94 b can be received in apertures 96 a, 96 b of the cradle plates 66 a, 66 b, respectively, in press fit arrangement, for example. The bearings 94 a, 94 b support generally cylindrical journal portions 98 (see FIG. 6B, and in which the left journal portion is obscured from view) of the crank assembly 82.

Although not illustrated, to maintain clearance between the frame 26 and the cradle plates 66 a, 66 b, at least one insert (e.g., formed of hardened steel) can be disposed on inner surfaces of each of the cradle plates 66 a, 66 b, which can engage complementary inserts (e.g., formed of bronze) disposed on opposing sides of the frame 26. The inserts can form a friction bearing that provides lateral support to the frame 26, throughout the range of motion between the normal and inclined positions.

The crank assembly 82 further includes a spindle 100, which extends through the apertures 96 a, 96 b. The crank arms 84 a, 84 b are secured to ends of the spindle 100. The journal portions 98 are generally concentric with respect to the spindle 100. As such, the frame 26 pivots about the axis of rotation 24 defined by the spindle 100. The crank assembly 82 can include two or more housing plates, and a plurality of holes 102 can be provided to allow the housing plates to be secured by fasteners (not shown).

Referring to FIG. 7, the crank assembly 82 is shown to include a right housing plate 104, a left housing plate 106, and a center housing plate 108 sandwiched between the housing plates 104, 106. Right and left inserts 110 a, 110 b include the journal portions 98 (again, with the left journal portion obscured from view). The inserts 110 a, 110 b further include flange portions 112 a, 112 b, which are received in complementary recesses 114 formed in the housing plates 104, 106 (the recess of the housing plate 106 is obscured from view). The inserts 110 a, 110 b can be rigidly fastened to the housing plates 104, 106, respectively. Outer seals 116 a, 116 b can be provided between the inserts 110 a, 110 b and the spindle 100. The inserts 110 a, 110 b at either side of the crank assembly 82 support spindle bearings 118 a, 118 b, respectively. The spindle bearings 118 a, 118 b in turn support ends of the spindle 100.

Between the housing plates 104, 106, inner seals 120 a, 120 b and spindle bushings 122 a, 122 b can be arranged on both sides of the spindle 100. A main gear 124 surrounds the spindle 100. At least one spring-loaded pawl 126 is located along the outer circumference of the spindle 100, and is arranged to engage teeth 128 that are located along the inner circumference of the main gear 124. The pawl 126 and the teeth 128 form a ratchet mechanism that allows the pedals 22 a, 22 b to drive rotary motion of the main gear 124 when pedaling forward, but disengages allowing the main gear 124 to continue rotating when pedaling ceases.

An idler gear 130 is arranged adjacent to and meshed with the main gear 124. The idler gear 130 is retained and supported by the housing plates 104, 106, and with idler gear bushings 132 a, 132 b arranged therebetween, respectively. The main gear 124 and the idler gear 130 form a gear pump that operates to draw hydraulic fluid from the inlet port 88, through a cavity 134 around an outer perimeter of the gears 124, 130, to the outlet port 86. Fluid conduits (not shown) formed in the center housing plate 108 connect the ports 86, 88 and the cavity 134. Gaskets 136 located in grooves 138 can be provided on either side of the center housing plate 108 and surrounding the cavity 134, ensuring a good seal between the housing plates 104, 106, 108 to prevent hydraulic fluid from leaking from the cavity 134.

Referring now to FIG. 8, a hydraulic fluid reservoir 140 is connected by a fluid line 142 to the inlet port 88 of the crank assembly 82. In various examples, the reservoir 140 can be located hidden in the frame 26, between the cradle plates 66 a, 66 b, or can be an external component attached to the base 12. Pedaling drives the hydraulic fluid out of the outlet port 86 to a fluid line 144, which delivers the pressurized fluid to a control valve module 146. The control valve module 146 can selectively deliver the fluid to the actuator 68 via a fluid line 148, or back to the reservoir 140 via a pressure relief line 150. Fluid is returned to the reservoir 140 from the actuator 68 via a fluid line 152.

The control device 80 can be operably linked to the crank assembly 82, the control valve module 146 and the actuator 68, either mechanically (e.g., linked with a cable mechanism(s)) or electronically (e.g., linked by wires, or wirelessly). By controlling the flow of hydraulic fluid between the crank assembly 82, the control valve module 146, and the actuator 68, the control device 80 can be used to selectively control the position of the frame 26 between the normal and the inclined positions. Furthermore, by restricting the flow of hydraulic fluid out of the crank assembly 82 using, for example, the control valve module 146, the control device 80 can be used to selectively control the resistance of the pedals 22 a, 22 b. As mentioned above, the resistance and the incline angle 78 of the frame 26 can be associated, or can be set independent of one another.

The control device 80 can also be linked to one or more sensors (not shown) located in the crank assembly 82, the control valve module 146, the actuator 68, or elsewhere. For example, the control device 80 can be linked to a sensor in the crank assembly 82 that provides information related to cadence. The control device 80 can also be linked to a sensor in the control valve module 146 that provides information related to pressure of the hydraulic fluid, which can be correlated to power output. The control device 80 can further be linked to a sensor in the actuator 68 that provides information related to incline angle 78. Various sensor arrangements are possible.

Referring now to FIG. 9, another crank assembly suitable for the stationary exercise bicycle 10 is shown generally at 200. The crank assembly 200 is configured to drive hydraulic fluid from inlet ports 202 a, 202 b to outlet ports 204 a, 204 b, as described in further detail below. The crank assembly 200 can be secured to the frame 26 of the stationary exercise bicycle 10 generally as described herein with reference to the crank assembly 82.

Similar to the crank assembly 82, the crank assembly 200 includes journal portions 206 and a spindle 208. The journal portions 206 are generally concentric with respect to the spindle 208. As such, in examples where the stationary exercise bicycle 10 includes the crank assembly 200, the frame 26 pivots about an axis of rotation defined by the spindle 208.

Referring to FIG. 10, the crank assembly 200 is shown to include a right housing plate 210 and a left housing plate 212. Right and left inserts 214 a, 214 b include the journal portions 206 (with the left journal portion obscured from view). The inserts 214 a, 214 b further include flange portions 216 a, 216 b, which are received in complementary recesses formed in the housing plates 210, 212. The inserts 214 a, 214 b can be rigidly fastened to the housing plates 210, 212, respectively. The inserts 214 a, 214 b at either side of the crank assembly 200 support spindle bearings 218 a, 218 b, respectively. The spindle bearings 218 a, 218 b in turn support ends of the spindle 208.

In the example illustrated, an O-ring 222 is seated in a groove provided in at least one of the housing plates 210, 212, and provides a seal therebetween. Cam elements 220 a, 220 b are arranged adjacent to one another, around the spindle 208. Drive keys 224 are disposed along the outer circumference of the spindle 208, and provide for locking rotational engagement between the cam elements 220 a, 220 b and the spindle 208.

In the example illustrated, piston elements 226 a, 226 b are arranged generally orthogonal to an axis of the spindle 208, and in registration with the cam elements 220 a, 220 b, respectively. Return springs 228 a, 228 b, held in place by spring clips 230 a, 230 b, bias the piston elements 226 a, 226 b to bear against the cam elements 220 a, 220 b, respectively. End seals 232 a, 232 b provide a seal between the piston elements 226 a, 226 b and a flange plate 234. The flange plate 234 is mounted to recesses 236, 238 of the housing plates 210, 212, and a gasket 240 provides a seal therebetween. A piston housing block 242 is mounted to the flange plate 234 and at least partially receives the piston elements 226 a, 226 b. A check valve block 244 is mounted to the piston housing block 242, and O-rings 246 a, 246 b provide seals therebetween.

In use, rotation of the spindle 208 causes corresponding rotation of the cam elements 220 a, 220 b. In the example illustrated, the cam elements 220 a, 220 b alternately activate a reciprocating movement of the piston elements 226 a, 226 b. Due to the arrangement of the cam elements 220 a, 220 b positioned offset from one another by 180°, motion of the piston elements 226 a, 226 b generally oppose one another. Thus, while the piston element 226 a is in a compression stroke, the piston element 226 b is alternately in a decompression or suction stroke, and vice versa.

During the compression stroke, the piston elements 226 a, 226 b move (by movement of the cam elements 220 a, 220 b) generally away from the spindle 208, forcing hydraulic fluid out of the respective piston element 226 a, 226 b to the outlet ports 204 a, 204 b via the check valve block 244. During the decompression stroke, the piston elements 226 a, 226 b move (by force of the return springs 228 a, 228 b) towards the spindle 208, drawing hydraulic fluid into the respective piston element 226 a, 226 b from the inlet ports 202 a, 202 b. In this manner, the crank assembly 200 acts as a pump that operates to draw hydraulic fluid between the inlet ports 202 a, 202 b to the outlet ports 204 a, 204 b. The crank assembly 200 can be implemented in a hydraulic system similar to the crank assembly 82 as described herein with reference to FIG. 8.

While the above description provides examples of one or more processes or apparatuses, it will be appreciated that other processes or apparatuses may be within the scope of the accompanying claims. 

We claim:
 1. A stationary exercise bicycle, comprising: a base; right and left pedals coupled to the base, and configured to rotate in operation about an axis of rotation; a frame having a rear end pivotally mounted to the base, and a forward end spaced apart from the rear end; a saddle coupled generally to the rear end of the frame; a handlebar coupled generally to the forward end of the frame; and an actuator coupling the frame to the base, the actuator configured to pivot the frame relative to the base about the axis of rotation.
 2. The stationary exercise bicycle of claim 1, wherein the actuator couples the forward end of the frame to the base.
 3. The stationary exercise bicycle of claim 2, wherein the actuator pivots the frame between normal and inclined positions.
 4. The stationary exercise bicycle of claim 3, wherein, in the inclined position, an incline angle of the frame is about 15 degrees.
 5. The stationary exercise bicycle of claim 3, wherein the actuator is a linear actuator.
 6. The stationary exercise bicycle of claim 5, further comprising a first pivotal connection coupling an upper end of the actuator to the forward end of the frame, and a second pivotal connection coupling a lower end of the actuator to the base.
 7. The stationary exercise bicycle of claim 6, further comprising right and left upstanding cradle plates mounted to the base, and a crank assembly pivotally supported between the cradle plates and secured to the frame
 8. The stationary exercise bicycle of claim 7, wherein the crank assembly comprises a spindle, and the right and left pedals are coupled to the spindle.
 9. The stationary exercise bicycle of claim 8, wherein each of the cradle plates comprises an aperture, and the spindle extends through the apertures.
 10. The stationary exercise bicycle of claim 9, wherein the frame comprises a seat tube, and first and second top tubes secured to the seat tube, and the crank assembly is secured between the seat tube and the first and second top tubes of the frame.
 11. The stationary exercise bicycle of claim 7, wherein the actuator comprises a hydraulic cylinder.
 12. The stationary exercise bicycle of claim 11, wherein the hydraulic cylinder and the crank assembly are connected so that hydraulic fluid power from the crank assembly causes the frame to pivot.
 13. The stationary exercise bicycle of claim 12, wherein the crank assembly comprises gears forming a gear pump.
 14. The stationary exercise bicycle of claim 12, wherein the crank assembly comprises at least one cam element coupled to the spindle, and at least one piston element coupled to the cam element.
 15. The stationary exercise bicycle of claim 12, further comprising a control device configured to move the actuator to pivot the frame.
 16. The stationary exercise bicycle of claim 15, wherein the control device is configured to control a resistance of the pedals.
 17. A stationary exercise bicycle, comprising: a base; a frame; a crank assembly pivotally coupling the frame to the base, the crank assembly comprising a spindle; right and left pedals mounted to the spindle, and configured to rotate in operation about an axis of rotation; and a hydraulic cylinder coupling the frame to the base, the hydraulic cylinder configured to pivot the frame relative to the base about the axis of rotation between normal and inclined positions.
 18. The stationary exercise bicycle of claim 17, wherein the crank assembly comprises gears forming a gear pump, and the hydraulic cylinder and the crank assembly are connected so that hydraulic fluid power from the crank assembly causes the frame to pivot between the normal and inclined positions.
 19. The stationary exercise bicycle of claim 17, wherein the crank assembly comprises at least one cam element coupled to the spindle, and at least one piston element coupled to the cam element, and the hydraulic cylinder and the crank assembly are connected so that hydraulic fluid power from the crank assembly causes the frame to pivot between the normal and inclined positions.
 20. A stationary exercise bicycle, comprising: a base; right and left pedals coupled to the base, and configured to rotate in operation about an axis of rotation; a frame coupled to the base, the frame comprising a saddle and a handlebar; and a linear actuator coupling the frame to the base, the linear actuator configured to pivot the frame relative to the base about the axis of rotation between normal and inclined positions. 